Micronutrients Needed by Crops Lee Jacobs Department of Crop and Soil Sciences Michigan State University

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Micronutrients Needed by Crops Lee
JacobsDepartment of Crop and Soil
SciencesMichigan State University

• presented at
• MWEA Biosolids Conference
• Bay City, Michigan
• February 21, 2008

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Classification of the Essential Nutrients for
Plant Growth
Macronutrients C, H, O from air and water N,
P, K, Ca, Mg, S from soil Primary
Secondary Micronutrients Fe, B, Mn, Cu, Zn,
Mo, Cl, Ni from soil
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Essential Major Elements Plants/Animals

• Major Plant Nutrients Major Animal Nutrients
• Carbon (C) Carbon (C)
• Hydrogen (H) Hydrogen (H)
• Oxygen (O) Oxygen (O)
• Nitrogen (N) Nitrogen (N)
• Phosphorus (P) Sulfur (S)
• Potassium (K) Calcium (Ca)
• Calcium (Ca) Phosphorus (P)
• Magnesium (Mg) Potassium (K)
• Sulfur (S) Magnesium (Mg)
• Sodium (Na)
• Chlorine (Cl)

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Essential Trace Elements Plants/Animals

• Trace Plant Nutrients Trace Animal Nutrients
• Boron (B) Copper (Cu)
• Copper (Cu) Iron (Fe)
• Iron (Fe) Manganese (Mn)
• Manganese (Mn) Molybdenum (Mo)
• Molybdenum (Mo) Zinc (Zn)
• Zinc (Zn) Arsenic (As)
• Chlorine (Cl) Chromium (Cr)
• Nickel (Ni) Cobalt (Co)
• Flourine (F)
• Essential for Some Plants Iodine (I)
• Cobalt (Co) Nickel (Ni)
• Silicon (Si) Selenium (Se)
• Sodium (Na) Silicon (Si)
• Vanadium (V) Tin (Sn)
• Vanadium (V)

Plants will not only absorb essential plant and
animal elements, but many non-essential
elements found in soils are also found in plant
tissue ash.
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Nutrient Levels in Plants

• Terms used to describe nutrient levels in plants
• Deficient when the concentration of an
  essential element is low enough to severely limit
  yield
• Critical range nutrient concentration in plant
  below which a yield response occurs when the
  essential nutrient is added
• Sufficient (optimal) nutrient concentration
  range when the yield will not increase when more
  of the essential nutrient is added, but plant
  tissue concentration can increase
• Excessive (toxic) when the concentration of an
  essential, or non-essential, element is high
  enough to reduce plant growth and yield

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(a)
(b)
Figure 2.5. Typical dose-response curves for (a)
essential elements (macronutrients
micronutrients) and (b) non-essential elements.
(Alloway,1995, p. 31)
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(1 10,000 ppm)
Havlin et al.,2005, p. 12
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Quantities of Micronutrients Needed

• 1) While micronutrients are required by a plant
  for growth, the amount needed is small in
  comparison to macro nutrients (N, P, K).
• 2) Nevertheless, deficiency of a micronutrient
  can be just as yield limiting as the deficiency
  of a macronutrient.

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Micronutrients

• Form Taken Major Concentration
• Element up by plants Source in plants
  (avg)
• Chloride (Cl) Cl- Precipitation 100 ppm
• Salts
• Iron (Fe) Fe2, Fe3 Soil minerals
  100 ppm
• Manganese (Mn) Mn2 Soil minerals 50 ppm
• Zinc (Zn) Zn2 Soil minerals, 20 ppm
• organic matter
• Boron (B) H3BO3 Organic matter
  20 ppm
• Copper (Cu) Cu2 Soil minerals 6 ppm
• organic matter
• Molybdenum (Mo) MoO42- Soil minerals
  0.1 ppm
• Nickel (Ni) Ni2 Soil minerals 0.01 ppm

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For optimum availability of all essential plant
nutrients, usually want to maintain soil pH at
6.5 or above by liming, but soil pH should be
kept below 7.0.
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Typical Concentrations in Soils

• Micronutrient Range Average
• Iron (Fe2, Fe3) 0.5 50 3 4
• Manganese (Mn2) 20 3,000 ppm 600 ppm
• Nickel (Ni2) 2 750 ppm 50 ppm
• Zinc (Zn2) 10 300 ppm 50 ppm
• Copper (Cu2) 2 100 ppm 9 ppm
• Boron (H3BO3) 2 200 ppm 50 ppm
• Molybdenum (MoO42-) 0.2 5.0 ppm 1.2 ppm
• Chloride (Cl-) highly variable

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Similar cycles occur for each of the cationic
micronutrients, as shown above for Fe2 and Fe3,
except only divalent forms of Mn2, Zn2, Cu2,
and Ni2 are taken up by plants.
Havlin et al., 2005, p. 245
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Fe and Mn in Soils

• 1) Solubility of Fe minerals is very low in
  soils, so Fe3 in solution is very low and much
  higher than Fe2 in well-drained, oxidized soils
  across common soil pHs.
• 2) Under waterlogged conditions, Fe3 can be
  reduced to Fe2
• 2 Fe2O3 ? 4 FeO O2
• 3) Mn2 is common in soil solution, but
  concentrations decrease as pH increases.
• 4) Mn2 concentration controlled mostly by MnO2,
  w/ 90 of the Mn2 organically complexed
  (chelated) Mn2 in solution can increase under
  acid, reducing conditions
• 5) Natural organic compounds in soil, or
  synthetic compounds added to soils can complex
  (chelate) Fe3, which can increase Fe in the soil
  solution and transport to roots by mass flow and
  diffusion.

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Havlin et al., 2005, p. 250
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MSU Extension Bulletin E-486
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• Table 1. Micronutrient sufficiency ranges in
  diagnostic tissue of selected crops.
• Element Corn Wheat Alfalfa
  Soybeans Potatoes Sugar Beets
• - - - - - - - - - -
  ppm - - - - - - - - -
  -
• Boron (B) 4-25 6-40 31-80
  21-55 15-40 26-80
• Copper (Cu) 6-20 6-50 11-30
  10-30 7-30
  11-40
• Iron (Fe) 21-250 11-300 31-250
  51-350 30-300 51-200
• Manganese (Mn) 20-150 16-200 31-100
  21-100 30-200 21-150
• Molybdenum (Mo) 0.1-2.0 0.03-5.0 1.0-5.0
  1.0-5.0 0.5-4.0
  0.15-5.0
• Zinc (Zn) 20-70 21-70 21-70
  21-50 30-100 19-60
• Chloride (Cl) 2,000-20,000
  (0.2-2.0)
• Nickel (Ni) 0.1-1.0
• Ranges taken from MSU Bulletin E-486, page 2,
  except general range for Cl and Ni taken from
  Havlin et al, 2005.

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Fe Deficiency Symptoms andToxicity in Plants

• 1) Plants contain 11-350 ppm. Deficiency not
  common for field and vegetable crops grown on
  soils with pH lt7.0
• 2) Fe is very immobile in plants, so deficiency
  symptoms appear in young leaves, causing stunted
  growth.
• 3) Young leaves develop interveinal chlorosis,
  similar to Mn deficiency.
• 4) Under severe Fe deficiency, leaves turn white
  and eventually die (necrosis).
• 5) Fe toxicity where plants accumulate gt300 ppm
  can occur when pH is lt5.0 and where soils are
  contaminated w/ soluble Fe salts.

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Figure 23. Iron-deficient corn. Light yellowing
of the terminal leaves, with interveinal
chlorosis of the leaves similar to that caused by
Mn deficiency. Seldom found in Michigan field
crops. More commonly found in woody plants,
ornamental and turf crops. (Bull. E-486, p. 14)
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Fe deficiency in a fescue lawn. (personal
communication, J.L. Havlin)
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Mn Deficiency Symptoms andToxicity in Plants

• 1) Plants contain 20-200 ppm Mn (normal), usually
  deficient if lt20 ppm, and usually toxic if gt300
  ppm.
• 2) Mn deficiency usually found on slightly acid
  (pH 6.6-7.0) or alkaline soils (pH gt7.0) may
  also occur when
• a) pH gt5.8 on organic soils black sands
• b) pH gt6.5 on mineral soils
• 2) Mn is immobile in plants, so deficiency
  symptoms appear in young leaves.
• 3) Young leaves develop interveinal chlorosis,
  similar to Fe deficiency.
• 4) Mn toxicity occurs in sensitive crops grown on
  acid soils liming can readily correct this
  problem in tissue, Mn concentrations gt300 ppm
  can be toxic

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Havlin et al., 2005
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Figure 4. Manganese-deficient dark red kidney
beans. Yellowing between the leaf veins. Veins
remain green. (Bull. E-486, p. 7)
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Typical Concentrations in Soils

• Micronutrient Range Average
• Iron (Fe2, Fe3) 0.5 50 3 4
• Manganese (Mn2) 20 3,000 ppm 600 ppm
• Nickel (Ni2) 2 750 ppm 50 ppm
• Zinc (Zn2) 10 300 ppm 50 ppm
• Copper (Cu2) 2 100 ppm 9 ppm
• Boron (H3BO3) 2 200 ppm 50 ppm
• Molybdenum (MoO42-) 0.2 5.0 ppm 1.2 ppm
• Chloride (Cl-) highly variable

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Similar cycles occur for Cu2 and Ni2, as shown
above for Zn2, to release divalent ions of each
metal into the soil solution for uptake by plants.
Havlin et al., 2005, p. 256
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Zn, Ni and Cu in Soils

• 1) Soil solution Zn2, Ni2, and Cu2 is low Zn,
  Ni and Cu solubility is pH dependent, as shown in
  the figure earlier.
• 2) Organic complexed (chelated) forms of Zn2,
  Ni2, and Cu2 can increase the concentrations of
  each metal in the soil solution to increase their
  diffusion to roots for plant uptake.

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Havlin et al., 2005, p. 250
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Zn, Ni and Cu in Soils

• 1) Soil solution Zn2, Ni2, and Cu2 is low Zn,
  Ni and Cu solubility is pH dependent, as shown in
  the figure above.
• 2) Organic complexed (chelated) forms of Zn2,
  Ni2, and Cu2 can increase the concentrations of
  each metal in the soil solution to increase their
  diffusion to roots for plant uptake.
• 3) Availability of Cu is more strongly controlled
  by soil organic matter (SOM). At lt8 SOM, Cu is
  adsorbed to organic mineral surfaces, but at
  gt8 SOM, Cu is adsorbed mostly on organic
  surfaces. Therefore, Cu deficiency is frequent
  w/ peat muck soils.

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Zn and Ni Deficiency Symptoms and Toxicity in
Plants

• 1) Zn deficiency is usually found on soils that
  are a) acidic sandy soils low in Zn, b) neutral,
  basic, or calcareous soils, and c) soils with
  high available P. Ni deficiency is seldom
  observed due to low plant requirements.
• 2) Zn and Ni are not readily translocated, so
  deficiency symptoms first appear in young leaves.
• 3) Zn and Ni toxicity can occur on acid soils, pH
  lt5.0, and/or where soils are contaminated with
  soluble Zn or Ni salts.
• 4) Zn concentrations are normally 20-150 ppm with
  lt20 ppm being deficient and gt300 ppm being toxic.
  
• 5) Ni concentrations are normally 0.1-1.0 ppm
  with gt50 ppm usually toxic. However, some plants
  are hyperaccumulators of Ni and leaves of these
  plants can contain gt1,000 ppm w/o toxicity.

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Figure 13. Zinc-deficient corn. Yellow or white
striping of the leaves usually developing near
the stalk. Plants are often stunted with
shortened internodes. Found most often on high
pH soils and organic soils. (Bull. E-486, p. 10)
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Havlin et al., 2005
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Cu Deficiency Symptoms and Toxicity in Plants

• 1) Cu deficiencies are not as common as other
  micronutrients but can occur in sensitive crops
  on low-Cu soils, because most soils in Michigan
  have sufficient Cu. Peaty soils are generally
  the only soils that can be deficient in Cu.
• 2) Cu is not readily translocated, so deficiency
  symptoms first appear in young leaves.
• 3) Cu toxicity is uncommon but can occur where
  soils are contaminated with high Cu materials or
  repeated use of Cu-containing pesticides.
• 4) Plants contain 6-50 ppm Cu with 5-20 ppm being
  normal, lt6 ppm usually deficient, and gt150 ppm
  usually toxic.

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Typical Concentrations in Soils

• Micronutrient Range Average
• Iron (Fe2, Fe3) 0.5 50 3 4
• Manganese (Mn2) 20 3,000 ppm 600 ppm
• Nickel (Ni2) 2 750 ppm 50 ppm
• Zinc (Zn2) 10 300 ppm 50 ppm
• Copper (Cu2) 2 100 ppm 9 ppm
• Boron (H3BO3) 2 200 ppm 50 ppm
• Molybdenum (MoO42-) 0.2 5.0 ppm 1.2 ppm
• Chloride (Cl-) highly variable

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A similar cycle occurs for H3BO3 and MoO42- as
for Cl-. Note that leaching is a
possible pathway however, no H3BO3 and MoO42-
inputs from rain occur, as occurs with Cl-.
Havlin et al., 2005, p. 280
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B, Mo and Cl in Soils

• 1) Total B in soils varies between 2-200 ppm,
  while total Mo in soils typically ranges between
  0.2-5 ppm. Nearly all Cl- in soils exists in the
  soil solution, which ranges in concentration from
  0.5 ppm in acid soils to gt6,000 ppm in
  saline/sodic soils.
• 2) H3BO3 is the predominant form in soil solution
  at pH range of 5 to 9. Organically complexed B is
  the largest potential source of plant available B
  in soils, which increases w/ increasing SOM.
• 3) MoO42-, HMoO4-, and H2MoO4 are forms found in
  soil solution with MoO42- and HMoO4-
  concentrations increasing as soil pH increases.
• 4) Cl in soils behaves very similar to NO3-,
  being very soluble and readily leaches.

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B, Mo and Cl Deficiency Symptoms and Toxicity in
Plants

• 1) B deficiency is usually found on sandy soils,
  organic soils some fine-textured lake bed soils
  (w/ alkaline subsoils). Very few soils in MI
  have need for Mo additions, except for peats,
  acid sandy soils organic soils w/ large amounts
  of bog Fe. Deficiency of Cl is rare.
• 2) B and Mo are immobile in plants, so deficiency
  symptoms appear in young leaves.
• 3) B toxicity is uncommon in most arable soils,
  unless excess amounts are added by fertilizers or
  contamination. Plants normally contain 20-100
  ppm B with lt15 ppm usually being deficient and
  gt200 ppm usually being toxic.

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B, Mo and Cl Deficiency Symptoms and Toxicity in
Plants (contd)

• 4) Plants normally contain 0.8-15 ppm Mo with
  lt0.5 ppm usually being deficient. Plants appear
  quite tolerant of high soil Mo, so there are no
  recordings of Mo toxicity under field conditions.
  However, excess amounts of Mo in forages are
  toxic to animals causing molybdenosis, a disease
  in cattle.
• 5) Plants normally contain 0.5-2.0 Cl
  (5,000-20,000 ppm) with lt70-700 ppm usually
  indicative of deficiency. Concentrations up to
  2.0 can be toxic for sensitive plants and gt4.0
  can be toxic for tolerant plants, although levels
  as high as 10 do occur with some salt-tolerant
  plants.

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Soil Testing and Fertilizer Additions of
Micronutrients

• 1) In Michigan, soil testing can be done for B,
  Cu, Fe, Mn and Zn to check for adequate
  availability of these nutrients for plant growth.
• 2) When availability is low, the following are
  rates normally recommended for crops that are
• nutrient highly responsive medium responsive
• B 1.5 - 3.0 lb/ac 0.5 1.0
  lb/ac
• Cu 3 6 lb/ac (organic soils) 1.5
  3.0 lb/ac
• Fe (foliar spray usually
  used at 0.5 1.0 lb/ac)
• Mn (4 8 lb/ac for mineral, 8 16 lb/ac
  for organic soils)
• Zn (3-5 lb/ac for soil pHgt7.5, 2-3 lb/ac
  for soil pH 6.7-7.4)